Multi-element synergistic doping modified sodium ion battery positive electrode material and preparation method thereof

Abstract

The invention belongs to the technical field of sodium-ion batteries, and particularly relates to a multi-element synergistically doped and modified sodium-ion battery positive electrode material and a preparation method thereof. The sodium ion battery positive electrode material provided by the invention is a P2 type layered oxide, the chemical general formula is Na < 0.67 + X > Ni < 0.33-(X + Y) Mn < 0.67-ZLiXCuYTiZO2, X is greater than 0 and less than or equal to 0.15, Y is greater than 0 and less than or equal to 0.15, and Z is greater than 0 and less than or equal to 0.15, and the sodium ion battery positive electrode material is prepared by taking a sodium source, a nickel source, a manganese source, a lithium source, a copper source and a titanium source as raw materials, carrying out ball milling, carrying out compression molding and then carrying out calcination treatment. The positive electrode material is synergistically doped with lithium, copper and titanium, has relatively high energy density, excellent cycle performance and excellent rate capability, and solves the problem that an existing P2 type layered oxide positive electrode material is poor in electrochemical stability and rate capability under high voltage.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sodium ion batteries, and more particularly to a multi-element synergistically doped modified sodium ion battery positive electrode material and a preparation method thereof. BACKGROUND

[0002] In recent years, the market of new energy is continuously increasing, and the demand is continuously improving. In order to match the demand of the new energy market, to accommodate wind power, photovoltaic and other new energy power generation, and to help the development of new energy vehicles, the requirement for energy storage is more and more urgent. Electrochemical energy storage is a convenient, fast and efficient energy storage method. At present, as the main electrochemical energy storage battery, the excessively high cost of lithium ion batteries and the uneven distribution of lithium ore are not conducive to the large-scale development of electrochemical energy storage. Therefore, it is urgent to find a cheap and abundant substitute to replace lithium ion batteries in the application of energy storage systems. Sodium ions are widely distributed and abundant in the earth, and are an excellent choice to replace lithium ion batteries.

[0003] At present, sodium ion battery positive electrode materials include layered transition metal oxides (LTMOs), polyanion (PA) compounds and prussian blue analogues (PBAs) compounds. Among them, sodium ion layered transition metal oxides are widely favored for commercialization due to their similar structure to lithium ion ternary positive electrode materials and high theoretical specific capacity. However, sodium ion layered oxide positive electrode materials have problems such as poor cycle stability and poor rate performance, which hinder their development in the commercialization process. How to solve these problems has become a difficult problem that technicians in the field need to overcome. SUMMARY

[0004] The purpose of the present application is to provide a multi-element synergistically doped modified sodium ion battery positive electrode material and a preparation method thereof, and more particularly to provide a lithium, copper and titanium synergistically doped modified sodium ion battery layered positive electrode material and a preparation method thereof, to solve the problems existing in the prior art.

[0005] To achieve the above purpose, the present application provides the following solutions:

[0006] One of the technical solutions of the present application: a multi-element synergistically doped modified sodium ion battery positive electrode material is provided, which is a P2-type layered oxide, and the chemical general formula is Na 0.67+X Ni 0.33-(X+Y) Mn 0.67-Z Li X Cu Y Ti Z O2, wherein 0X≤0.15, 0Y≤0.15, and 0Z≤0.15.

[0007] The low valence of lithium element can cause the transition of trivalent manganese ions to tetravalent manganese ions, thereby reducing the damage of Jahn-Teller distortion to the material structure, and lithium ions can fill into specific positions of the sodium layer, reducing the risk of layer collapse and improving the sodium ion diffusion efficiency. The copper element can form a strong covalent bond in the transition metal layer, which can reduce layer sliding and structure collapse after sodium ions are deintercalated, and the copper element can reduce the cation migration phenomenon of iron elements, stabilize the phase structure, and alleviate the irreversible phase change process. The function of titanium element is similar to that of copper element, and the strong electronegativity of titanium element can reduce the activity of lattice oxygen and inhibit the loss of oxygen under high voltage.

[0008] Single-element doping often has limited effect or other negative effects in solving problems, while multi-element doping can achieve all-round performance improvement through synergistic effect. For example, copper element and titanium element as electrochemically inert elements together inhibit phase change and reduce layer sliding and layer collapse after sodium is deintercalated; lithium element can migrate to sodium site to accelerate ion transmission, and titanium element expands the distance between transition metal layers, together reducing the sodium ion diffusion barrier, thereby improving the sodium ion diffusion coefficient. Multi-element co-doping improves the configurational entropy of the material, forming a unique "high-entropy effect". The high-entropy material reduces the Gibbs free energy, so that the entire material system tends to form a single stable phase structure, avoiding the generation of harmful second phase structure, and improving the stability of the material in the cycle process; the "cocktail effect" produced by synergy makes the gain of multi-element doping much greater than the linear superposition of single-element, in order to achieve the above purpose, the present application finally selects the scheme of co-doping of lithium element, copper element and titanium element.

[0009] The second technical scheme of the present application provides a preparation method of the above-mentioned multi-element synergistically doped modified sodium ion battery positive electrode material, comprising the following steps:

[0010] The sodium source, nickel source, manganese source, lithium source, copper source and titanium source are used as raw materials, ball milled, then pressed into a shape, and then calcined to obtain the multi-element synergistically doped modified sodium ion battery positive electrode material.

[0011] Further, the sodium source includes at least one of sodium hydroxide, sodium carbonate, sodium acetate, sodium oxalate, sodium nitrate, sodium citrate and sodium alginate.

[0012] Further, the nickel source includes at least one of nickel oxide, nickel acetate, nickel nitrate, nickel sulfate, nickel oxalate and nickel carbonate.

[0013] Further, the manganese source includes at least one of manganese sesquioxide, manganese trioxide, manganese carbonate, manganese nitrate, manganese chloride, manganese sulfate, manganese acetate and manganese oxalate.

[0014] Further, the lithium source includes at least one of lithium hydroxide, lithium carbonate, lithium oxalate, lithium acetate, lithium nitrate and lithium citrate.

[0015] Further, the copper source includes at least one of copper hydroxide, copper carbonate, copper oxalate, copper acetate, copper nitrate, copper citrate, copper sulfate, cuprous oxide and copper oxide.

[0016] Further, the titanium source includes at least one of titanium dioxide, titanium sulfate and titanium nitrate.

[0017] Further, the ball milling parameters are as follows: the medium is an organic solvent, the ratio of material to beads is 1:5-20, the rotation speed is 300-600 rpm, and the time is 3-10 h.

[0018] Optionally, the organic solvent includes at least one of acetone, ethanol, methanol, ethyl acetate, N,N-dimethylformamide and dimethyl sulfoxide.

[0019] Further, the pressure of the press forming is 10-20 MPa.

[0020] Further, the heating rate of the calcination treatment is 2-10 ℃ / min, the calcination temperature is 700-1000 ℃, and the calcination time is 12-20 h.

[0021] The third technical scheme of the present application provides an electrode for a sodium ion battery, wherein the active component of the electrode includes the above-mentioned sodium ion battery cathode material modified by multi-element synergistic doping.

[0022] The fourth technical scheme of the present application provides application of the above-mentioned sodium ion battery cathode material modified by multi-element synergistic doping or the above-mentioned sodium ion battery cathode in a sodium ion battery.

[0023] The fifth technical scheme of the present application provides a sodium ion battery, wherein the cathode of the sodium ion battery is the above-mentioned electrode for a sodium ion battery.

[0024] The present application discloses the following technical effects:

[0025] The present application provides a sodium ion battery layered cathode material modified by lithium, copper and titanium synergistic doping, which has high energy density, excellent cycle performance and excellent rate performance, and solves the problem of poor rate performance of the existing P2 type layered oxide cathode material under high voltage.

[0026] The sodium ion battery positive electrode material modified by multi-element synergistic doping in the application improves the structural entropy of the P2 type layered oxide through lithium, copper and titanium synergistic doping, and the synergistic effect of the three causes the change of the structure of the electrode material, thereby reducing the P2-O2 phase change of the electrode material in the charging and discharging process at high voltage and improving the stability of the material at high voltage. At the same time, the high-entropy structure also provides a favorable environment for the rapid embedding and extraction of sodium ions, and improves the rate performance.

[0027] The layered positive electrode material (the sodium ion battery positive electrode material modified by multi-element synergistic doping) is prepared by the solid phase method, the preparation process is simple, mass production is facilitated, and the application prospect is good. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which form a part of this application, are used to provide a further understanding of the application, and are incorporated herein for explanation along with the descriptions of the illustrative embodiments thereof. In the drawings:

[0029] Figure 1 The XRD diagram of the positive electrode material prepared for Example 1 and Comparative Example 1.

[0030] Figure 2 The SEM diagram of the positive electrode material prepared for Example 1.

[0031] Figure 3 The SEM diagram of the positive electrode material prepared for Comparative Example 1.

[0032] Figure 4 The EDS diagram of the positive electrode material prepared for Example 1.

[0033] Figure 5 The cycle performance comparison diagram of the positive electrode materials of Example 1 and Comparative Example 1.

[0034] Figure 6 The rate performance comparison diagram of the positive electrode materials of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0035] Now, a variety of exemplary embodiments of the application will be described in detail, which should not be considered as limiting the application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the application.

[0036] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0037] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0038] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0039] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0040] Unless otherwise specified, all raw materials and reagents used in the specific embodiments of this invention are commercially available products.

[0041] Unless otherwise specified, room temperature and normal temperature in the specific embodiments of this invention refer to 20-30℃.

[0042] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0043] Example 1

[0044] The preparation steps of sodium-ion battery cathode material modified by multi-element synergistic doping are as follows:

[0045] S1. Weigh 1.60g sodium carbonate, 0.6337g nickel oxide, 1.9331g manganese trioxide, 0.0887g lithium carbonate, 0.1770g cuprous oxide, and 0.2241g titanium dioxide. Mix them evenly in ethanol solvent, then add them to a ball mill jar. Set the bead ratio to 1:10, the rotation speed to 400 rpm, and the time to 10 hours. After ball milling, transfer the mixture to a vacuum oven for storage and record it as the precursor.

[0046] S2. The precursor from step S1 is pressed into tablets at 15 MPa in a tablet press, then placed in a muffle furnace and heated to 950°C at a heating rate of 5°C / min, held at that temperature for 15 hours, and then allowed to cool naturally to 100°C to obtain the multi-element synergistic doping modified sodium-ion battery cathode material, denoted as Na. 0.73 Ni 0.21 Mn 0.60 Li 0.06 Cu 0.06 Ti 0.07 O2.

[0047] Example 2

[0048] The preparation steps of sodium-ion battery cathode material modified by multi-element synergistic doping are as follows:

[0049] S1. Weigh 1.53g sodium carbonate, 0.6337g nickel oxide, 1.9331g manganese trioxide, 0.0443g lithium carbonate, 0.2655g cuprous oxide and 0.2241g titanium dioxide, mix them evenly in ethanol solvent, and then add them to a ball mill jar. Set the bead ratio to 1:15, the speed to 500 rpm, and the time to 10 hours. After ball milling, transfer the mixture to a vacuum oven for storage and record it as the precursor.

[0050] S2. The precursor from step S1 is pressed into tablets at 10 MPa in a tablet press, then placed in a muffle furnace and heated to 900°C at a heating rate of 4°C / min, held at that temperature for 15 hours, and then allowed to cool naturally to 100°C to obtain the multi-element synergistic doping modified sodium-ion battery cathode material, denoted as Na. 0.70 Ni 0.21 Mn 0.60 Li 0.03 Cu 0.09 Ti 0.07 O2.

[0051] Example 3

[0052] The preparation steps of sodium-ion battery cathode material modified by multi-element synergistic doping are as follows:

[0053] S1. Weigh 1.661g sodium carbonate, 0.6337g nickel oxide, 1.9331g manganese trioxide, 0.1330g lithium carbonate, 0.0885g cuprous oxide and 0.2241g titanium dioxide, mix them evenly in ethanol solvent, and then add them to a ball mill jar. Set the bead ratio to 1:9, the speed to 500 rpm, and the time to 10 hours. After ball milling, transfer the mixture to a vacuum oven for storage and record it as the precursor.

[0054] S2. The precursor from step S1 is pressed into tablets at 20 MPa using a tablet press, then placed in a muffle furnace and heated to 950°C at a heating rate of 4°C / min, held at that temperature for 15 hours, and then allowed to cool naturally to 100°C to obtain the multi-element synergistic doping modified sodium-ion battery cathode material, denoted as Na. 0.76 Ni 0.21 Mn 0.60 Li 0.09 Cu 0.03 Ti 0.07 O2.

[0055] Example 4

[0056] The preparation steps of sodium-ion battery cathode material modified by multi-element synergistic doping are as follows:

[0057] S1. Weigh 1.60g sodium carbonate, 0.6337g nickel oxide, 1.8687g manganese trioxide, 0.0887g lithium carbonate, 0.1770g cuprous oxide and 0.2881g titanium dioxide, mix them evenly in ethanol solvent, and then add them to a ball mill jar. Set the bead ratio to 1:10, the speed to 500 rpm, and the time to 10 hours. After ball milling, transfer the mixture to a vacuum oven for storage and record it as the precursor.

[0058] S2. The precursor from step S1 is pressed into tablets at 15 MPa in a tablet press, then placed in a muffle furnace and heated to 950°C at a heating rate of 4°C / min, held at that temperature for 15 hours, and then allowed to cool naturally to 100°C to obtain the multi-element synergistic doping modified sodium-ion battery cathode material, denoted as Na. 0.73 Ni 0.21 Mn 0.58 Li 0.06 Cu 0.06 Ti 0.09 O2.

[0059] Comparative Example 1

[0060] The preparation steps for sodium-ion battery cathode materials are as follows:

[0061] S1. Weigh 1.4684g sodium carbonate, 0.9958g nickel oxide and 2.1586g manganese trioxide, mix them evenly in ethanol solvent, and then add them to a ball mill jar. Set the bead ratio to 1:10, the speed to 400 rpm and the time to 10 hours. After ball milling, transfer the mixture to a vacuum oven for storage and record it as the precursor.

[0062] S2. The precursor from step S1 is pressed into tablets at 15 MPa in a tablet press, then placed in a muffle furnace and heated to 950°C at a heating rate of 5°C / min, held at that temperature for 15 hours, and then allowed to cool naturally to 100°C to obtain the sodium-ion battery cathode material, denoted as Na. 0.67 Ni 0.33 Mn 0.67 O2.

[0063] Comparative Example 2

[0064] The preparation steps for sodium-ion battery cathode materials are as follows:

[0065] S1. Weigh 1.7266g sodium carbonate, 0.6337g nickel oxide, 1.9331g manganese trioxide, 0.1774g lithium carbonate and 0.2241g titanium dioxide, mix them evenly in ethanol solvent, and then add them to a ball mill jar. Set the bead ratio to 1:15, the speed to 500 rpm, and the time to 10 hours. After ball milling, transfer the mixture to a vacuum oven for storage and record it as the precursor.

[0066] S2. The precursor from step S1 is pressed into tablets at 10 MPa in a tablet press, then placed in a muffle furnace and heated to 900°C at a heating rate of 4°C / min, held at that temperature for 15 hours, and then allowed to cool naturally to 100°C to obtain the sodium-ion battery cathode material, denoted as Na. 0.79 Ni 0.21 Mn 0.60 Li 0.12 Ti 0.07 O2.

[0067] Comparative Example 3

[0068] The preparation steps for sodium-ion battery cathode materials are as follows:

[0069] S1. Weigh 1.4684g sodium carbonate, 0.6337g nickel oxide, 1.9331g manganese trioxide, 0.3540g cuprous oxide and 0.2241g titanium dioxide, mix them evenly in ethanol solvent, and then add them to a ball mill jar. Set the bead ratio to 1:9, the speed to 500 rpm, and the time to 10 hours. After ball milling, transfer the mixture to a vacuum oven for storage and record it as the precursor.

[0070] S2. The precursor from step S1 is pressed into tablets at 20 MPa in a tablet press, then placed in a muffle furnace and heated to 950°C at a heating rate of 4°C / min, held at that temperature for 15 hours, and then allowed to cool naturally to 100°C to obtain the sodium-ion battery cathode material, denoted as Na. 0.67 Ni 0.21 Mn 0.60 Cu 0.12 Ti 0.07 O2.

[0071] Comparative Example 4

[0072] The preparation steps for sodium-ion battery cathode materials are as follows:

[0073] S1. Weigh 1.4684g sodium carbonate, 0.2716g nickel oxide, 2.1586g manganese trioxide, 0.1774g lithium carbonate and 0.3540g cuprous oxide, mix them evenly in ethanol solvent, and then add them to a ball mill jar. Set the bead ratio to 1:9, the speed to 500 rpm, and the time to 10 hours. After ball milling, transfer the mixture to a vacuum oven for storage and record it as the precursor.

[0074] S2. The precursor from step S1 is pressed into tablets at 20 MPa in a tablet press, then placed in a muffle furnace and heated to 950°C at a heating rate of 4°C / min, held at that temperature for 15 hours, and then allowed to cool naturally to 100°C to obtain the sodium-ion battery cathode material, denoted as Na. 0.67 Ni 0.09 Mn 0.67 Li 0.12 Cu 0.12 O2

[0075] Comparative Example 5

[0076] The preparation steps for sodium-ion battery cathode materials are as follows:

[0077] S1. Weigh 1.4684g sodium carbonate, 0.6337g nickel oxide, 2.1586g manganese trioxide, and 0.1774g lithium carbonate, mix them evenly in ethanol solvent, and then add them to a ball mill jar. Set the bead ratio to 1:9, the rotation speed to 500 rpm, and the time to 10 hours. After ball milling, transfer the mixture to a vacuum oven for storage and record it as the precursor.

[0078] S2. The precursor from step S1 is pressed into tablets at 20 MPa in a tablet press, then placed in a muffle furnace and heated to 950°C at a heating rate of 4°C / min, held at that temperature for 15 hours, and then allowed to cool naturally to 100°C to obtain the sodium-ion battery cathode material, denoted as Na. 0.67 Ni 0.21 Mn 0.67 Li 0.12 O2

[0079] Comparative Example 6

[0080] The preparation steps for sodium-ion battery cathode materials are as follows:

[0081] S1. Weigh 1.4684g sodium carbonate, 0.6337g nickel oxide, 2.1586g manganese trioxide, and 0.3540g cuprous oxide, mix them evenly in ethanol solvent, and then add them to a ball mill jar. Set the bead ratio to 1:9, the speed to 500 rpm, and the time to 10 hours. After ball milling, transfer the mixture to a vacuum oven for storage and record it as the precursor.

[0082] S2. The precursor from step S1 is pressed into tablets at 20 MPa in a tablet press, then placed in a muffle furnace and heated to 950°C at a heating rate of 4°C / min, held at that temperature for 15 hours, and then allowed to cool naturally to 100°C to obtain the sodium-ion battery cathode material, denoted as Na. 0.67 Ni 0.21 Mn 0.67 Cu 0.12 O2

[0083] Comparative Example 7

[0084] The preparation steps for sodium-ion battery cathode materials are as follows:

[0085] S1. Weigh 1.4684g sodium carbonate, 0.9958g nickel oxide, 1.9331g manganese trioxide, and 0.2241g titanium dioxide, mix them evenly in ethanol solvent, and then add them to a ball mill jar. Set the bead ratio to 1:9, the rotation speed to 500 rpm, and the time to 10 hours. After ball milling, transfer the mixture to a vacuum oven for storage and record it as the precursor.

[0086] S2. The precursor from step S1 is pressed into tablets at 20 MPa in a tablet press, then placed in a muffle furnace and heated to 950°C at a heating rate of 4°C / min, held at that temperature for 15 hours, and then allowed to cool naturally to 100°C to obtain the sodium-ion battery cathode material, denoted as Na. 0.67 Ni 0.33 Mn 0.60 Ti 0.07 O2

[0087] Comparative Example 8

[0088] The preparation steps for sodium-ion battery cathode materials are as follows:

[0089] S1. Weigh 1.4684g sodium carbonate, 0.6337g nickel oxide, 1.9331g manganese trioxide, 0.3318g potassium carbonate, 0.4104g cobalt trioxide, and 0.2132g chromium trioxide, mix them evenly in ethanol solvent, and then add them to a ball mill jar. Set the bead ratio to 1:9, the rotation speed to 500 rpm, and the time to 10 hours. After ball milling, transfer the mixture to a vacuum oven for storage and record it as the precursor.

[0090] S2. The precursor from step S1 is pressed into tablets at 20 MPa in a tablet press, then placed in a muffle furnace and heated to 950°C at a heating rate of 4°C / min, held at that temperature for 15 hours, and then allowed to cool naturally to 100°C to obtain the sodium-ion battery cathode material, denoted as Na. 0.67 Ni 0.21 Mn 0.60 K 0.06 Co 0.06 Cr 0.07 O2

[0091] Test case

[0092] Figure 1 The figures show the XRD patterns of the cathode materials prepared in Example 1 and Comparative Example 1. As can be seen from the figures, the peak positions are basically consistent, with no impurity peaks, proving that both are P2-type layered oxides. The intensity of the peaks at different positions varies, indicating that lithium, copper, and titanium are synergistically doped into the crystal structure of the material and have an impact.

[0093] Figure 2 The image shows a SEM image of the cathode material prepared in Example 1.

[0094] Figure 3 The image shows the SEM image of the cathode material prepared in Comparative Example 1.

[0095] Depend on Figure 2 and Figure 3 It can be seen that the material morphology of Example 1 is hexagonal layered plate type, which is formed by the agglomeration of primary particles into secondary particles; the overall morphology and particle distribution of Comparative Example 1 are not much different from those of Example 1, and the two still maintain the same morphological structure.

[0096] Figure 4 The image shows the EDS (Electrode Spectroscopy) diagram of the cathode material prepared in Example 1. As can be seen from the diagram, lithium, copper, titanium, and other elements are uniformly distributed throughout the material.

[0097] Tests were conducted using the 2032 model button cell as a benchmark:

[0098] The prepared positive electrode material was used as the positive electrode active material, polyvinylidene fluoride (PVDF) was used as the binder, conductive carbon black (SuperP) was used as the conductive agent, and N-methylpyrrolidone (NMP) was used as the solvent. The positive electrode active material, binder and conductive agent were stirred and mixed in a mass ratio of 8:1:1 to form a uniform slurry. The prepared positive electrode slurry was uniformly coated on aluminum foil using a preparation device, and then transferred to a vacuum drying oven at 120°C for vacuum drying for 12 hours. The thickness to be achieved by rolling the electrode sheet was calculated based on the compaction density, and the rolling process was carried out. The rolled electrode sheet was cut into uniformly thick electrode sheets with a diameter of 11 mm using a cutting machine, and assembled into coin cells in a vacuum glove box. The sodium sheet was used as the counter electrode, a GF / D glass fiber separator was used, and a NaClO4-based electrolyte was used. The battery was assembled in a glove box filled with argon gas, where the water and oxygen levels were both below 0.1 ppm. Electrochemical tests were conducted using the mass of the positive electrode material as the mass of the active material. The test temperature was 25°C, the electrochemical test window was 2.0-4.5V, and 1C = 173 mAh / g.

[0099] Figure 5 The graph shows a comparison of the cycling performance of the cathode materials in Example 1 and Comparative Example 1. As can be seen from the graph, the coin cell prepared in Example 1 retains 70.76% of its capacity after 1000 cycles at 25°C, 2.0-4.3V, and 5C (1C = 173 mA / g); while the coin cell prepared in Comparative Example 1 retains only 37.22% of its capacity after 1000 cycles at 25°C, 2.0-4.3V, and 5C.

[0100] Figure 6 The graph shows a comparison of the rate performance of the cathode materials in Example 1 and Comparative Example 1. As can be seen from the graph, at higher rates, Example 1 is significantly superior to Comparative Example 1, and the capacity of Example 1 remains above 85 mAh / g even at 10C. This demonstrates that the synergistic doping of lithium, copper, and titanium greatly improves their long-cycle performance and rate performance.

[0101] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0102] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sodium-ion battery cathode material modified by multi-element synergistic doping, characterized in that, It is a P2-type layered oxide with the general chemical formula Na. 0.67+X Ni 0.33-(X+Y) Mn 0.67-Z Li X Cu Y Ti Z O2, where 0 < X ​​≤ 0.15, 0 < Y ≤ 0.15, and 0 < Z ≤ 0.

15.

2. A method for preparing a sodium-ion battery cathode material modified by multi-element synergistic doping as described in claim 1, characterized in that the steps include... include: Using sodium, nickel, manganese, lithium, copper, and titanium sources as raw materials, the materials are ball-milled, pressed into shape, and then calcined to obtain the multi-element synergistic doping modified sodium-ion battery cathode material.

3. The preparation method according to claim 2, characterized in that, The sodium source includes at least one of sodium hydroxide, sodium carbonate, sodium acetate, sodium oxalate, sodium nitrate, sodium citrate, and sodium alginate; and / or, the nickel source includes at least one of nickel oxide, nickel acetate, nickel nitrate, nickel sulfate, nickel oxalate, and nickel carbonate; and / or, the manganese source includes at least one of manganese trioxide, manganese tetroxide, manganese carbonate, manganese nitrate, manganese chloride, manganese sulfate, manganese acetate, and manganese oxalate.

4. The preparation method according to claim 2, characterized in that, The lithium source includes at least one of lithium hydroxide, lithium carbonate, lithium oxalate, lithium acetate, lithium nitrate, and lithium citrate; and / or, the copper source includes at least one of copper hydroxide, copper carbonate, copper oxalate, copper acetate, copper nitrate, copper citrate, copper sulfate, cuprous oxide, and copper oxide; and / or, the titanium source includes at least one of titanium dioxide, titanium sulfate, and titanium nitrate.

5. The preparation method according to claim 2, characterized in that, The parameters for the ball mill are as follows: the medium is an organic solvent, the ball-to-material ratio is 1:5 to 20, the rotation speed is 300-600 rpm, and the time is 3-10 h.

6. The preparation method according to claim 5, characterized in that, The organic solvent includes at least one of acetone, ethanol, methanol, ethyl acetate, N,N-dimethylformamide, and dimethyl sulfoxide.

7. The preparation method according to claim 2, characterized in that, The pressing pressure is 10-20 MPa; and / or the calcination heating rate is 2-10 °C / min, the calcination temperature is 700-1000 °C, and the calcination time is 12-20 h.

8. An electrode for a sodium-ion battery, characterized in that, The active component of the electrode for the sodium-ion battery includes the sodium-ion battery cathode material modified by multi-element synergistic doping as described in claim 1.

9. The application of the sodium-ion battery cathode material modified by multi-element synergistic doping as described in claim 1 or the sodium-ion battery cathode as described in claim 8 in a sodium-ion battery.

10. A sodium-ion battery, characterized in that, The positive electrode of the sodium-ion battery is the electrode for a sodium-ion battery as described in claim 8.

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