Positive electrode material and preparation method and application thereof

Abstract

The invention provides a positive electrode material and a preparation method and application thereof. The positive electrode material is of a particle structure, and a positive electrode material main body comprises a P2 / O3 double-phase structure and a flexible amorphous interfacial film covered on the particle surface. The sodium ion battery prepared according to the positive electrode material has the advantages of long cycle life and air durability, the preparation process is simple, and the comprehensive performance and practicability of the positive electrode material are improved. The sodium ion battery prepared based on the positive electrode material has the advantages of high energy density, long cycle life, good low temperature performance and strong wide temperature range applicability.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries, and particularly relates to a cathode material, a preparation method thereof, and an application thereof. Background Art

[0002] The development of low-cost, high-efficiency, long-life, and safe renewable energy storage systems has become a research hotspot. With the continuous expansion of the market scale, the uneven distribution of resources such as lithium, nickel, and cobalt globally has caused cost and supply problems, restricting the sustainable development of lithium-ion battery (LIBs) technology. Due to the abundant sodium resources, easy access, and low cost, the development of sodium ion batteries (SIBs) has received increasing attention. As rechargeable batteries, SIBs have suitable redox potentials. In addition, Na does not alloy with Al, and SIBs can use Al as the current collector for the positive / negative electrode materials, reducing the battery cost. Therefore, SIBs are expected to become the next generation of high-energy-density and low-cost energy storage technologies. However, the actual capacity of SIBs is low and the cycle life is short, and there is still a large room for development compared with LIBs. The key characteristics of the battery (such as specific capacity, cycle performance, and working voltage) are mainly determined by the inherent electrochemical characteristics of the electrode materials. Therefore, the main problem in the SIB system is to find suitable electrode materials, especially cathode materials, which largely determine the energy density, cycle life, and safety performance of the battery.

[0003] Currently, the cathode materials approaching commercialization mainly include layered transition metal oxides (Na x TMO2, 0 < x ≤ 1), Prussian blue / white compounds, and polyanionic compounds. Prussian blue / white compounds have crystallization water and environmental protection problems. Polyanionic compounds have low energy density and poor conductivity, but better structural stability, prominent cycle life, and high voltage. Layered transition metal oxides are easy to synthesize, have adjustable composition, and high energy density, but poor cycle and air stability. Although the "best choice" of cathode materials is still under debate. However, Na x TMO2 materials have high energy density and excellent wide-temperature adaptability, making them considered most likely to be used as the cathode materials for the next generation of high-performance SIBs. Among Na x TMO2 materials, 3d transition metal elements except scandium (Sc) have redox activity. Na x TMO2 materials have various layered stacking sequences and Na coordination environments, which are beneficial to the mixing of different types of TM elements. The + radius of Na is larger than that of Li + radius by a large margin, making the Na layer prone to separation from the TM layer. In Na xDuring the charge and discharge process of the TMO2 electrode, the TMO2 layer slides and some Na + The coordination environment changes, that is, the mutual transformation between octahedral sites and prismatic sites. Due to the weak strength of Na-O bond, as Na + The removal of O atoms increases the repulsive force between the layers of layered Na x TMO2 is more likely to undergo structural rearrangement to reduce the free energy of the system. x OP or PO phase transitions are often observed in TMO2 electrodes. x TMO2 is widely present and seriously affects the cycle life of the battery. x TMO2 material has poor air stability. x When TMO2 material is exposed to air, it will deteriorate, causing Na to precipitate from the bulk structure and deposit on the surface of the material in the form of NaOH and Na2CO3, which will cause gelation during the preparation of electrode slurry. This not only increases the difficulty of coating, but may also lead to increased internal resistance and gas production in the battery, affecting battery performance. Therefore, it is necessary to build a uniform chemically stable interface. Structural stability and air stability are the key factors for Na x TMO2 materials are key factors in practical applications. Therefore, the key to the technology of SIBs is to develop oxide materials with higher capacity and more stable bulk and interface. Summary of the Invention

[0004] The technical problem solved by the present invention is to provide a positive electrode material, its preparation method and application. The positive electrode material comprises a main P2 / O3 dual-phase symbiotic structure and a surface nano-amorphous layer. The sodium ion battery prepared by this method has the advantages of high gram capacity, good air stability, and excellent cycle and rate performance. At the same time, the preparation method is simple and has universal applicability, which improves the practicality of the positive electrode material. The sodium ion battery assembled based on this positive electrode material has high energy density, long cycle life and good air tolerance, and can be used in wide temperature range application scenarios.

[0005] The present application provides a positive electrode material, which has a particle structure. The main body of the positive electrode material includes a P2 / O3 two-phase structure and the particle surface is covered with a flexible amorphous interface film.

[0006] The P2 / O3 dual-phase symbiotic structure in this application enhances the stability of the crystal structure, suppresses volume changes and microcrack propagation caused by harmful phase transitions, and enhances ion diffusion dynamics. Furthermore, the flexible amorphous interface film improves the material's air tolerance. As a result, the sodium-ion battery prepared using this structure significantly improves the battery's cycle life and energy density, and enhances its adaptability to a wide temperature range.

[0007] Preferably, the chemical formula of the positive electrode material is Na xTMX y O2@Na u X v O w , wherein TM is one or more of Ni, Fe, Mn, Co, Ti, Cu, V, Cr, Zr, and Nb, X is one or more of B, S, Si, and P, 0.8<x<1.0, 0.01<y<0.3, and u, v, and w are all greater than 1.

[0008] The positive electrode material provided by the present application is composed of a non-metallic cation X having a high ionic potential. n+ (B 3+ , Si 4+ , P 5+ , S 6+ ) Synchronously induce the main body to construct a P2 / O3 symbiotic structure and coat the surface with a chemically stable amorphous interface film to obtain Na with good bulk / interface stability x In addition, the formation of the P2 / O3 dual-phase structure is due to the component heterogeneity and local "cation potential" (Φ) caused by thermodynamic / kinetic competition during the solid phase reaction. cation =Φ TM / Φ Na ·Φ O ) difference, resulting in a specific composition of the O3 / P2 symbiotic structure "cation potential" close to the boundary between the O3 and P2 single-phase regions. When the sodium content in the system is higher than 0.8, due to the strong electrostatic shielding effect of high sodium sites on transition metals, traditional transition metal cations are difficult to effectively regulate the "cation potential" of the bulk structure through electronic polarization, resulting in it always being in the O3 single-phase region. The present invention innovatively introduces non-metallic cations X n+ (B 3+ , Si 4+ , P 5+ , S 6+ ), directionally anchored in the tetrahedral interstitial sites of transition metal oxygen accumulation, breaking through the threshold limit of "cation potential". As a result, even under high sodium content conditions (x>0.8), the P2 / O3 dual-phase symbiotic structure was successfully constructed, solving the bottleneck problem of traditional doping mechanisms in high sodium systems that are difficult to control phase structure.

[0009] Preferably, the ratio of the P2 / O3 dual-phase structure in the main body is 0.0%-100%, and the range does not include the two end points.

[0010] The ratio of the P2 / O3 dual phase structure in the main body of the present application, that is, the content ratio of the P2 phase to the O3 phase ranges from 0.0% to 100%. xTMO2 can be divided into two major topological families: the O type (Octahedral) and the P type (Prismatic). Among them, the O3 type (0.7 < x ≤ 1.0) crystals construct periodic octahedral sodium layers with an ABCABC oxygen stacking sequence (space group R3m). The P2 type (x < 0.7) constructs prismatic sodium layer channels with an ABBA oxygen layer stacking sequence (space group P63 / mmc). The P2 / O3 biphasic structure, that is, the uneven distribution of the P2 and O3 phases along two different crystal plane indices. The P2 / O3 biphasic symbiotic structure can suppress structural strain through the "interlocking effect", reduce lattice mismatch, and reduce the sliding of the TMO2 layer. There is a critical value of 1.62 for the ratio of the Na layer spacing (d(O-Na-O)) to the TM layer spacing (d(O-TM-O)) in the materials with the O3 and P2 structures. When the ratio is higher than 1.62, the P2 phase is usually formed, and when it is lower than 1.62, the O3 phase is easily formed. The change in the layer spacing is essentially the result of the interaction between the electrostatic attraction and electrostatic repulsion between the NaO2 layer and the TMO2 layer. Increasing the Na content can enhance the electrostatic attraction between the Na layers, making d(O-Na-O) smaller, thus obtaining the O3 phase; conversely, the electrostatic repulsion plays a major role in the P2 phase. By quantifying the cation electron cloud density and polarization ability, using the "cation potential" (Φ cation =Φ TM / Φ Na ·Φ O ) can effectively predict the competition relationship between the O3 / P2 structures. At low sodium content, high Φ cation triggers strong covalency and electron delocalization between the transition metal layers, driving the formation of the P2-type structure. High sodium content stabilizes the O3-type structure by shielding the transition metal layer repulsion. The non-metal cations X n+ (B 3+ 、Si 4+ 、P 5+ 、S 6+ ) have high ionic potentials (27.3, 10.0, 29.4, 20.7), which are much higher than the ionic potentials of common transition metal ions (Mn 4+ (7.55), Ti 4+ (6.61), Ni 3+ (5.36), Fe 3+ [[ID=二十八]](4.65), Ni 2+ (2.90)). In addition, non-metal cations can occupy the tetrahedral interstitial sites of the oxygen stacking in the cathode material. Therefore, by regulating the occupation of the tetrahedral interstitial sites of the non-metal cations in the transition metal layer, it is possible to break through the limited electron polarization ability of conventional metal ions and induce a high-sodium type Na xTMO2 material produces P2 / O3 symbiotic structure. More importantly, non-metallic cations can be deposited on the particle surface in the form of polyanions to form a flexible amorphous film. Among them, X (B, S, Si, P) is non-metallic. In the positive electrode material, non-metallic cations X n+ (B 3+ 、Si 4+ 、P 5+ 、S 6+ )exist.

[0011] Preferably, the Na u X v O w It is an amorphous nanolayer, and its molar percentage of the sodium ion battery positive electrode material is 0.1%-10%.

[0012] The appropriate amount of Na in this application u X v O w Amorphous materials (0.5%-5.0%) can achieve uniform coating, buffer structural stress, provide more active sites for ion embedding, and shorten the ion transmission distance. u X v O w A rich amorphous-crystalline heterogeneous interface network is formed with the nanocrystalline region, showing strong cation adsorption and lower ion diffusion energy barrier, thereby accelerating charge carrier migration and enhancing electrode electrochemical activity. u X v O w Amorphous materials have good corrosion resistance, can isolate the influence of moisture, and improve the storage performance of the base material.

[0013] The present application provides a method for preparing a positive electrode material, comprising the following steps: step S1: mixing a sodium source, a transition metal source, and a heterogeneous non-metallic source in a preset ratio, forming a mixed solution by solution mixing, and spray-drying the mixed solution to prepare a precursor; and step S2: calcining the precursor obtained in step S1, and cooling the calcined precursor to 200° C. to obtain the positive electrode material.

[0014] The heterogeneous metal source in this application is one or more of S, P, Si and B. The cathode material prepared in this application needs to be formed by a spray drying process. First, a spherical particle material precursor can be prepared by spray drying. Secondly, spray drying can achieve a uniform distribution of the heterogeneous metal source throughout the spherical particles, and then after high-temperature calcination, the main P2 / O3 dual-phase symbiotic structure and the surface amorphous Na u X v O wCoating. Heterogeneous metals distributed near the surface tend to react with the sodium source, precipitating on the surface to form a coating. Meanwhile, the heterogeneous metals in the bulk phase tend to occupy interstitial sites of oxygen accumulation tetrahedrons, precisely controlling the "cation potential" to induce the formation of a P2 / O3 dual-phase intergrowth structure in the bulk and forming a flexible amorphous interface film on its particle surface.

[0015] Preferably, in step S1, the preset ratio of the sodium source, transition metal source and heterogeneous metal source is 0.8-1.1:1.0:0.01-0.1, and the concentration of the solution is 0.5-5.0 mol / L.

[0016] Preferably, the feed rate for spray drying is 0.1-10 L / min, and the physical and chemical temperature (i.e., inlet / outlet air temperature) is 100-400°C. The feed rate refers to the feed rate of the mixed solution; the solution is an aqueous solution of a sodium source, a transition metal source, and a heterogeneous non-metallic source, such as a mixed aqueous solution of sodium carbonate, nickel sulfate, and boric acid.

[0017] Preferably, the calcination temperature in step S2 is 400-1200° C., the calcination atmosphere is air, the sintering time is 10-40 h, and the calcination heating rate is 1-20° C. / min.

[0018] Preferably, the sodium source is one or more of sodium carbonate, sodium hydroxide, sodium nitrate, sodium bicarbonate, sodium sulfate, sodium oxalate, sodium phosphate, sodium dihydrogen sulfate, disodium hydrogen phosphate, and sodium acetate; the transition metal source is one or more of nickel nitrate, nickel sulfate, nickel acetate, ferric nitrate, ferric sulfate, ferric acetate, manganese nitrate, manganese sulfate, manganese acetate, cobalt nitrate, cobalt sulfate, cobalt acetate, titanium sulfate, copper nitrate, copper sulfate, copper acetate, vanadium nitrate, vanadium sulfate, vanadium acetate, chromium nitrate, chromium sulfate, chromium acetate, zinc nitrate, zinc sulfate, zinc acetate, neodymium nitrate, neodymium sulfate, and neodymium acetate; and the heterogeneous non-metallic source is one or more of boric acid, phosphoric acid, sulfuric acid, and silicic acid.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The multifunctional integrated structure constructed by the present invention achieves a synergistic improvement in multiple performance aspects. The P2 / O3 dual-phase symbiotic structure enhances the stability of the crystal structure, suppresses volume changes and microcrack propagation caused by harmful phase transitions, and enhances ion diffusion dynamics. In addition, the flexible amorphous interface film improves the material's air tolerance. As a result, the prepared positive electrode material significantly improves the battery's cycle life and energy density, and enhances its wide temperature range adaptability.

[0021] 2. The preparation method of the present invention has the advantages of simple process and easy operation. By combining spray drying and high-temperature solid-phase sintering, the simultaneous construction of a bulk P2 / O3 dual-phase symbiotic structure and a surface nano-amorphous film can be achieved without the need for complex equipment and harsh process conditions. Moreover, the wide selection of raw materials and low cost facilitate large-scale industrial production, providing strong support for the commercial application of sodium-ion battery cathode materials.

[0022] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0024] Figure 1 The NaNi prepared in Example 1 of the present invention 0.4 Fe 0.2 Mn 0.4 XRD pattern of O2@Na2B4O7 material;

[0025] Figure 2 The NaNi prepared in Example 1 of the present invention 0.4 Fe 0.2 Mn 0.4 XRD pattern of O2 material;

[0026] Figure 3 The NaNi prepared in Example 1 of the present invention 0.4 Fe 0.2 Mn 0.4 SEM image of O2@Na2B4O7 material;

[0027] Figure 4 The NaNi prepared in Example 1 of the present invention 0.4 Fe 0.2 Mn 0.4 SEM images of O2 materials;

[0028] Figure 5 The NaNi prepared in Example 1 of the present invention 0.4 Fe 0.2 Mn 0.4 EDS images of O2@Na2B4O7 materials;

[0029] Figure 6 The NaNi prepared in Example 1 of the present invention 0.4 Fe 0.2 Mn 0.4 HR-TEM image of O2@Na2B4O7 material;

[0030] Figure 7 The NaNi prepared in Example 1 of the present invention 0.4 Fe 0.2 Mn 0.4 HR-TEM images of O2 materials;

[0031] Figure 8 The NaNi prepared in Example 1 and Comparative Example 1 of the present invention 0.4 Fe 0.2 Mn 0.4 O2@Na2B4O7 materials and NaNi 0.4 Fe 0.2 Mn 0.4 Cycling performance diagram of 2Ah soft-pack battery assembled with O2 material. DETAILED DESCRIPTION

[0032] The following description sets forth numerous specific details to facilitate a thorough understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific implementations disclosed below.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to belong to the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. In the embodiments, unless otherwise specified, the means used are conventional means in the art. The terms "comprising", "including" or any other variations thereof used herein are intended to cover non-exclusive inclusions. For example, a composition, step, method, product or device comprising the listed elements need not be limited to only those elements, but may include other elements that are not clearly listed or elements inherent to such a composition, step, method, product or device. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] In the examples of the present invention, all experimental raw materials used are conventional commercial products. In the examples of the present invention, all equipment and instruments used can be purchased on the market or prepared using existing technologies.

[0035] Example 1: Step S1: Sodium nitrate, nickel nitrate, ferric nitrate, manganese nitrate, and boric acid were weighed in a stoichiometric ratio of 1.05:0.4:0.2:0.4:0.05 to prepare a 0.5 mol / L solution. The feed rate was set to 0.5 L / min, the inlet air temperature was set to 200° C., and the outlet air temperature was set to 300° C. The precursor material was collected at the outlet;

[0036] Step S2: The precursor material collected in step S1 is transferred to a kiln, air is pumped in by a blower, the heating rate is 2°C / min, and the temperature is kept at 450°C for 5 hours, then the temperature is raised to 900°C and kept for 15 hours, and then the temperature is lowered to 200°C to obtain NaNi, a sodium ion battery positive electrode material with a multifunctional integrated structure. 0.4 Fe 0.2 Mn 0.4 O2@Na2B4O7;

[0037] Comparative Example 1: Step S1: Sodium nitrate, nickel nitrate, iron nitrate, and manganese nitrate were weighed in a stoichiometric ratio of 1.05:0.4:0.2:0.4 to prepare a 0.5 mol / L solution. The feed rate was set to 0.5 L / min, the inlet air temperature was set to 200°C, and the outlet air temperature was set to 300°C. The precursor materials were collected at the outlet;

[0038] Step S2: The precursor material collected in step S1 is transferred to a kiln, air is pumped in by a blower, the heating rate is 2°C / min, and the temperature is kept at 450°C for 5 hours, then raised to 900°C and kept for 15 hours, and then cooled to 200°C to obtain the sodium ion battery positive electrode material NaNi. 0.4 Fe 0.2 Mn 0.4 O2;

[0039] Under the same conditions, the physicochemical indicators of the layered oxide positive electrode materials obtained in Example 1 and Comparative Example 1 and the electrochemical performance of the sodium ion batteries prepared therefrom were compared.

[0040] NaNi prepared in Example 1 0.4 Fe 0.2 Mn 0.4 XRD patterns of O2@Na2B4O7 materials Figure 1 As shown in FIG, the diffraction peaks at 16.3°, 33.1°, 35.5°, 36.8°, 41.7°, 45.1°, 53.3°, 62.9°, and 65.5° belong to the typical O3 phase, and the diffraction peak at 15.8° represents the P2 phase. 0.4 Fe 0.2 Mn 0.4 XRD of O2 materials Figure 2As shown, the diffraction peaks at 16.3°, 33.1°, 35.5°, 36.8°, 41.7°, 45.1°, 53.3°, 62.9°, and 65.5° belong to the typical O3 phase, and the P2 phase does not appear.

[0041] The cathode materials prepared in Example 1 and Comparative Example 1 were subjected to SEM analysis, and the results were as follows: Figure 3 and 4 As shown in the figure, it was found that the morphology of both was spherical particles formed by the aggregation of flakes.

[0042] The NaNi prepared in Example 1 0.4 Fe 0.2 Mn 0.4 The O2@Na2B4O7 material was tested by EDS, and the results are as follows Figure 5 As shown, NaNi 0.4 Fe 0.2 Mn 0.4 The O2@Na2B4O7 material is enriched with nickel, iron, manganese, sodium and boron. The positive electrode materials prepared in Example 1 and Comparative Example 1 were characterized by HR-TEM. The results are as follows: Figure 6 and 7 As shown, the NaNi prepared in Example 1 0.4 Fe 0.2 Mn 0.4 The surface of O2@Na2B4O7 material has a uniform nano-amorphous layer, and the main body is a P2 / O3 two-phase symbiotic structure, while the NaNi prepared in Comparative Example 1 0.4 Fe 0.2 Mn 0.4 O2 material only has O3 phase.

[0043] The positive electrode materials prepared in Example 1 and Comparative Example 1 were assembled into 2Ah soft-pack batteries and subjected to cycle life testing. The main production process includes positive electrode slurry (the ratio of positive electrode material, carbon nanotube conductive paste, and PVDF is 95%:2.5%:2.5%), negative electrode slurry (the ratio of hard carbon material, carbon nanotube conductive paste, and PVDF is 90%:4%:6%), rolling, slitting, winding, shelling, liquid injection, and formation to prepare the soft-pack batteries. Subsequent electrical performance testing was conducted on a Neware battery tester.

[0044] The cycle life test of 2Ah soft pack batteries assembled with the positive electrode materials prepared in Example 1 and Comparative Example 1 is as follows: Figure 8 As shown, the voltage range is 2.0-4.2V, the test current is 2A, and Example 1 can still maintain a capacity retention rate of 91.8% after 500 cycles, while the capacity retention rate of Comparative Example 1 under the same test conditions is only 54.2%, indicating that the sodium ion battery prepared by the positive electrode material prepared by the present application has better cycle life stability.

[0045] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A positive electrode material, characterized in that: The positive electrode material is a particle structure, the main body of the positive electrode material includes a P2 / O3 two-phase structure, and the particle surface is covered with a flexible amorphous interface film.

2. The positive electrode material according to claim 1, characterized in that: The chemical formula of the positive electrode material is Na x TMX y O2@Na u X v O w , wherein TM is one or more of Ni, Fe, Mn, Co, Ti, Cu, V, Cr, Zr, and Nb, X is one or more of B, S, Si, and P, 0.8<x<1.0, 0.01<y<0.3, and u, v, and w are all greater than 1.

3. The positive electrode material according to claim 1, wherein: The ratio of the P2 / O3 dual-phase structure in the main body is 0.0%-100%, and the range does not include the end points.

4. The positive electrode material according to claim 2, characterized in that: The Na u X v O w The amorphous nanolayer accounts for 0.5% to 5.0% of the molar percentage of the positive electrode material of the sodium ion battery.

5. A method for preparing the positive electrode material according to any one of claims 1 to 4, characterized in that: Step S1: mixing a sodium source, a transition metal source, and a heterogeneous non-metallic source in a preset ratio, forming a mixed solution by solution mixing, and spray drying the mixed solution to prepare a precursor; Step S2: calcining the precursor obtained in step S1, and cooling to 200° C. after calcination to obtain the positive electrode material.

6. The method for preparing the positive electrode material according to claim 5, wherein: In step S1, the preset ratio of the sodium source, transition metal source and heterogeneous metal source is 0.8-1.1:1.0:0.01-0.1, and the concentration of the solution is 0.1-10 mol / L.

7. The method for preparing the positive electrode material according to claim 5, wherein: The feed rate of the spray drying is 0.1-10 L / min, and the physical and chemical temperature is 100-400°C.

8. The method for preparing the positive electrode material according to claim 5, wherein: The calcination temperature in step S2 is 400-1200° C., the calcination atmosphere is air, the sintering time is 10-40 hours, and the calcination heating rate is 1-20° C. / min.

9. The method for preparing the positive electrode material according to claim 5, wherein: The sodium source is one or more of sodium carbonate, sodium hydroxide, sodium nitrate, sodium bicarbonate, sodium sulfate, sodium oxalate, sodium phosphate, sodium dihydrogen sulfate, disodium hydrogen phosphate, and sodium acetate; the transition metal source is one or more of nickel nitrate, nickel sulfate, nickel acetate, ferric nitrate, ferric sulfate, ferric acetate, manganese nitrate, manganese sulfate, manganese acetate, cobalt nitrate, cobalt sulfate, cobalt acetate, titanium sulfate, copper nitrate, copper sulfate, copper acetate, vanadium nitrate, vanadium sulfate, vanadium acetate, chromium nitrate, chromium sulfate, chromium acetate, zinc nitrate, zinc sulfate, zinc acetate, neodymium nitrate, neodymium sulfate, and neodymium acetate; and the heterogeneous non-metallic source is one or more of boric acid, phosphoric acid, sulfuric acid, and silicic acid.

10. A use of the positive electrode material according to any one of claims 1 to 4, characterized in that: The positive electrode material is used for preparing sodium ion batteries.

Images